Its still possible that they may run both shows. I mean isn't that exactly what's going on with Young Justice and New Teen Titans.
Not exactly, since those go in very different directions; Young Justice
is an older-skewing action drama, while Teen Titans Go
is straight comedy for younger viewers. Also, they only have two main characters in common and so aren't really about the same team. Conceptually and demographically, they fill very different niches. If Avengers Assemble
really exists, then it's almost entirely built around characters who are already part of the A:EMH core cast (Falcon being the exception), and it's the same kind of action-adventure-based show. So it would be a lot more redundant having them both on the air at the same time.